When a W/O type emulsion formed by stirring a mixture of reinforcing fibers, cement, water, and a vinyl monomer solution containing dissolved therein a surface active agent and a polymerization catalyst is extrusion molded by using a fishtail die or a coat hanger die, the directions of the reinforcing fibers are liable to become random and thus, it is difficult to obtain moldings having desired strength characteristics. This tendency is particularly remarkable in the case of extrusion-molding tabular materials having a relatively wide width and a thick thickness.
That is, in the case of forming tabular materials having a relatively wide width by extrusion-molding, the emulsion is spread on both sides by means of the die to form a tabular molding. The plastic concrete obtained by hardening and drying the emulsion molding thus formed is a porous and light-weight material but in this case, the reinforcing fibers contained in the emulsion are, as a matter of course, directed in the width wise direction. Thus, the bending strength of the plastic concrete moldings obtained is high in the width wise direction and weak in the lengthwise direction, which causes problems as building materials for practical purposes. Also, when the thickness of tabular moldings to be molded is over the length of reinforcing fibers, the reinforcing fibers are partially directed to the thickness direction and the reinforcing fibers thus directed to the thickness direction do not give the reinforcing effect in the lengthwise direction.
About tabular moldings for building materials, etc., it is actually adventageous considering from the stand point of the balance in strength that the moldings have a high bending strength in the lengthwise direction as compared to the width wise direction. Thus, for meeting the requirement in strength for building materials as described above, it has been desired that the reinforcing fibers are dispersed in plane direction and the ratio of reinforcing fibers directed to the lengthwise direction is high.